A switching contact arrangement has been disclosed in U.S. Pat. No. 2,777,921. In the case of the device which has been mentioned, the contact force which acts between the switching contacts is increased in particular by compensating as far as possible for forces in opposite directions, that is to say forces which disconnect the switching contacts from one another. These disturbance forces are dependent on the magnitude of the current flowing via the switching contacts.
In the case of switching contacts which abut against one another, such as those which are used in particular in low-voltage circuit breakers, these contact-lifting forces always occur because they are physically unavoidable high current density forces. However, undesirable opening of the switching contacts is not permissible in the case of selective circuit breakers, that is to say those which have to carry a short-circuit current for a specific time without disconnection of the switching contacts.
U.S. Pat. No. 2,777,921 includes incisions are arranged in the conductor pieces to which the switching contacts are fitted, such that mutually parallel current paths are formed which exert an attractive effect on one another. These counteract the lifting high current density forces and entirely or partially compensate for them. Although these incisions obviously represent an effective means for overcoming the described problem, they lead to an increase in the size of the switching contact arrangement and can adversely affect its mechanical robustness.
It is also known for the contact force in a switching contact system to be increased by way of a current-dependent force which occurs in any case (U.S. Pat. No. 4,636,762). For this purpose, a flexible conductor, which is required in any case in order to connect the moveable switching contact to a stationary connecting piece, is supported on a loop which is connected to the moveable switching contact. It is supported in such a way that a torque which acts in the closing direction is transmitted to the moveable switching contact, which is arranged on a contact mount such that it can pivot.
However, this highly effective arrangement requires additional parts, which significantly increase the moving mass of the moveable part of the switching contact arrangement. They thus necessitate greater opening forces for the switching processes.